Los Angeles & Salt Lake / Union Pacific 4-10-2 Locomotives in the USA

Class FTT-1 (Locobase 289)

Data from "Three-Cylinder 4-10-2 Locomotives for the SP and UP", Railway Age, Volume 79, No 6 (8 August 1925), pp. 268-271; and tables in the 1930 Locomotive Cyclopedia, supplemented by the LA&SL 1 - 1928 Locomotive Diagram book (the Salt Lake Route) supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (The 1930 Locomotive Cyclopedia was another source, but Locobase went with the railroad's data; the differences were not striking.) (Many thanks to Chris Hohl for his 29 April 2015 email spotting the difference in stroke for the center cylinder from the one originally published in Locobase. Hohl also pointed out UP diagrams commented that the class originally burned coal; by 1928, however, the entire class were oil-burners traililng the tenders shown in the Locobase specs.)

The 8000 was produced in April 1925 as works number 66169. The 8800-8808 were manufactured in May 1926 with Alco works numbers 66726-66734.

By the Union Pacific's reckoning, these "Overlands" (others called them "Southern Pacifics") weren't particularly successful engines. Their three-cylinder layout - outside actuated by Walschaert, inside by Gresley conjugated valve gear - was mechanically complicated and the wheelbase was too rigid. The center cylinder inclined at 9 1/2 degrees to clear the first axle and drive the second. The outside cylinders drove the third axle. An unusual visual difference from many other locomotives was the straight bottom edge given to the smokebox, which allowed easier access to the third cylinder.

The design used a Worthington 4-BL feed water heater.

Yet, the even bigger three-cylinder 4-12-2s from Alco dominated the prairies a few years later, which suggests that the Overlands suffered as much from being the pathfinders and a foreign road's design as anything else. See Locobase 288 for Alfred Bruce's positive assessment of the arrangement as it operated on the Espee.

In 1942, the class was "remodeled" from a three-cylinder to a two-cylinder type, these measuring 27" diameter by 32" stroke. For the result, see Locobase 13994.

Class FTT-1 - 2-cylinder (Locobase 13994)

Data from UP 11 - 1946 supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also the Challenger models account at [] and Wikipedia. (Thanks to Chris Hohl for his 2 June 2015 email correcting the tender's fuel and water capacities.)

Locobase 289 describes these unusual freighters as they were delivered in their three-cylinder configuration. Wikipedia quotes from James E Boynton's Three Barrels of Steam (Glenwood: Felton) on the problems presented by the floating bushings associated with the center cylinder.

Challenger notes that the 1942 program to remove the center cylinder and its Gresley conjugated link resulted in a noticeably large sand dome over the second and third axles and a fully round smokebox. A raised boiler pressure compensated to a large degree for the lost of cylinder volume.

Used in several regions, the class had joined the 9000s (three-cylinder 4-12-2) on the prairies in Kansas when they began retiring. Most had had the center driver replaced with a Boxpok main driver.

5094 and 5096 were the first to go out of service in 1948, followed by 5098-5099 in 1949. Then came a 5-year delay before 5095 was withdrawn in 1953 with the rest (5090-5093, 5097) retiring in 1954.